Combinations of hydroxyalkyl-n-methyltaurines and anionic sufactants as synergistic emulsifiers

ABSTRACT

EMULSIFYING AGENTS CHARACTERIZED BY UNUSUAL MILDNESS TOWARD THE SKIN ARE DISCLOSED WHICH CONSIST ESSENTIALLY OF A SYNERGISTIC COMBINATION OF A WATER SOLUBLE TAURINE SALT OF THE GENERAL FORMULA:   R1-CH(OH)-CH2-N(CH3)-CH2-CH2-SO3M   WHEREIN R1 IS AN ALKYL RADICAL HAVING FROM 12 TO 18 CARBON ATOMS OR AN OXAALKYL RADICAL HAVING THE FORMULA, CNH2N+1-O-CH2, N BEING 11 TO 17, AND M IS A WATERSOLUBILLIZING CATION AND A SURFACE ACTIVE ORGANIC SULFATE OR SULFONATE DETERGENT WHICH MAY BE AN AMIDOMETHANESULFONATE, AN ACYL ISETHIONATE, OR AN N-(ACYLOXYEHTYL) SULFOACETAMIDE. THE TAURINE SALT AND THE DETERGENT ARE PRESENT IN A SPECIFIED WEIGHT RATIO TO OBTAIN MAXIMUM AGE TIMES AND BETTER FOAMING PROPERTIES.

United States Patent US. Cl. 252-526 5 Claims ABSTRACT OF THE DISCLOSURE Emulsifying agents characterized by unusual mildness toward the skin are disclosed which consist essentially of a synergistic combination of a water soluble taurine salt of the general formula:

wherein R is an alkyl radical having from 12 to 18 carbon atoms or an oxaalkyl radical having the formula, C H -O-CH n being 11 to 17, and M is a watersolubilizing cation and a surface active organic sulfate or sulfonate detergent which may be an amidomethanesulfonate, an acyl isethionate, or an N-(acyloxyethyl) sulfoacetamide. The taurine salt and the detergent are present in a specified weight ratio to obtain maximum synergism.

This application is a continuation-in-part of our copending application Ser. No. 828,002, filed May 26, 1969, now US. 3,649,543, which in turn is a continuation-inpart of our application Ser. No. 573,192, filed Aug. 18, 1966, now abandoned.

This invention relates to a novel emulsifier, and more particularly, concerns compositions comprising a synergistic combination of hydroxyalkyl-N-methyltaurines with surface active organic sulfate and sulfonate detergents. These compositions have markedly improved characteristics which promote the formation and stabilization of oil and water emulsions which exhibit unusual mildness toward the skin.

It is Well known in the art that surface active compounds in general act as emulsifying agents and are of primary importance in stabilizing oil-in-water or water-inoil emulsification. The ability to form such emulsions is an important property for dish-washing purposes as well as for a variety of other applications.

The preparation and utility of hydroxyalkyl-N-methyltaurines as active detergent ingredients has been disclosed in the Cahn et al. Canadian Pat. No. 701,363. However, it has been heertofore unknown that these materials exhibit unusually strong synergistic effects when taken in combination with organic sulfates and sulfonates as emulsifiers for oil and water systems. The combined materials are many times more effective as an emulsifying system than either of the individual materials alone. These combinations are also unexpectedly mild detergents, and hence especially suitable for dishwashing purposes.

The salts of the taurines employed in the present invention have the following formula:

in which R is an alkyl radical having from about 12 to about 18 carbon atoms or an oxaalkyl radical of the formula C H OCH n being from 11-17 carbon atoms, and M is a Water-solubilizing cation. The watersolubilizing cation used may be any of those well-known in the art, such as the alkali metal ions, ammonium ions, or the substituted ammonium ions, such as trimethylammonium, triethanolammonium, or morpholinium. Obviously, sodium, potassium, and ammonium are preferred for reasons of economy and availability. The alkyl group of the N-(Z-hydroxyalkyl)-N-methyltaurines may be either straight or branched chain and may be derived from either synthetic or natural sources. Typical compounds include, but are not limited to, N-(Z-hydroxyalkyl)-N-methyltaurines (HAMT) of the above formula in which the radical R has 12-18 carbons as well as taurines in which R is C H O-CH n being from 11 to 17.

The surface active organic sulfate and sulfonate detergents which may be used in the present invention include salts of the water-solubilizing cations mentioned above with a surface active organic detergent selected from the group consisting of (l) Amidomethanesulfonates of the formula.

0 R J-NH-CHzSOaM (2) Acyl isethionates of the formula 0 R--i /-OCH:CHzSO -M (3) N-(acyloxyethyl) sulfoacetamides of the formula wherein R in the foregoing formulas, represents an aliphatic hydrocarbon radical having about 8 to about 20 carbon atoms, and M is a water-solubilizing cation. The hydrocarbon radical can be Substituted with functional groups such as a carboxylic acid or ether group and it may be saturated or unsaturated. Moreover, the aliphatic portion of the organic radical may be either a branched chain group derived from the older synthetic processes, such as polymerization of propylene, or it may be a straight chain group whereby the property of biodegradability can be obtained.

To obtain the greatest synergistic effects, the N-methyltaurine and detergent salts of the present invention should be present in a specified weight ratio ranging from about 1:3 to about 3:1, the precise ratio depending upon the sulfate or sulfonate detergent ingredient. More particularly, it has been found quite unexpectedly that combinations of taurine salts according to the invention, with amidomcthanesulfonate and acyl isethionate detergents as described herein in a weight ratio of about 1:1 to 1:3, taurine to detergent, and N-(acyloxyethyl) sulfoacetamidc detergents as described herein in a weight ratio of about 1:3, exhibit good synergistic properties in oil emulsification. For instance, in a typical formulation based upon the combination of a taurine and a sulfate or sulfonate detergent as described above, there may be from about 2% to about 35% of each of the taurine and the sulfate or sulfonate detergent components, up to 15% of an amide of a fatty acid in which one or both of the hydrogens of the amide nitrogen are replaced by lower alkyl or lower alkanol groups, and up to about 55% of an inorganic or organic detergency builder to enhance the emulsifying activity of the combination of the present invention. In typical compositions employing emulsifiers in combination with other components, the total of the taurine and the sulfate or sulfonate will normally be between about and about 40% by weight of the composition.

Typical amides which may be mentioned include, but are not limited to lauric monoethanol amide, lauric diethanol amide and lauric isopropanol amide. In other amides the lauric group may be replaced by myristoyl, palmitoyl, stearoyl, oleoyl, gadoloyl, erucopyl, etc., or mixtures of the foregoing, such as mixtures of lauroyl and myristoyl, and mixtures derived from naturally occurring fats and oils, such as coconut oil and tallow. In addition to the amides mentioned above, the unsubstituted amides, such as lauramide or the unsubstituted amide derived from coconut oil, may be used in granular products.

The inorganic builders contemplated are those commonly used in detergent formulations. Such builders include, but are not limited to, the alkali metal tripolyphosphates, tetraphosphates, hexametaphosphates, septaphosphates and decaphosphates, such as pentasodium triphosphate. In addition, certain orthophosphates and pyrophosphates such as potassium, sodium and ethanol, diethanol and triethanol pyrophosphates are useful. Other inorganic compounds include alkali metal and ammonium silicates, carbonates, chlorides, sulfates and borates, and the alkaline salts of nitrilotriacetic acid. Examples are sodium silicate, bentonite, sodium carbonate monohydrate, sodium and potassium chloride, sodium and ammonium sulfate, sodium borate and the like.

Other adjuvants which may be used without altering the essential nature of this invention include, but are not limited to, the cellulosic anti-soil redeposition aids such as methylcellulose, hydroxymethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, and hydroxypropyl cellulose. Certain organic polymers such as sodium polyacrylate and polyvinyl alcohol and the like have been found useful as builders in addition to some organic esters such as ethylene glycol monostearate and methyl palmitate. Higher fatty acid amides such as palmitylethanolamide, myristylethanolamide, laurylethanolamide, oleylethanolamide, myristamide, lauramide, stearamide, lauric diethanolamide, higher fatty acid amides of monoisopropanolamine (e.g. capyryl, lauroyl and myristoyl isopropanolamide) and amide type mixtures prepared from mixtures of higher fatty acids derived from various fats, oils and waxes of animal, marine or Vegetable origin may also be used as organic builders. Other amides suitable for use in our invention are N,N bis(lower alkylol) higher fatty acid amides such as N,N bis(Z-hydroxyethyl) lauramide, N,N bis(2- hydroxyethyl) myristamide, N,N bis(2-hydroxyethyl) coconut fatty acid amide, N,N bis(2,3-dihydroxypropyl) lauramide, N,N bis(2,3-dihydroxypropyl) myristamide, N,N bis(3-hydroxypropyl) lauramide, N,N bis(3-hydroxypropyl) capramide, N,N bis(Z-hydroxypropyl) lauramide,

4 N,N bis(2-hydroxypropyl) myristamide, N,N bis(4-hydroxybutyl) lauramide and the like.

In the foregoing it will be obvious to those skilled in the art that of the alkali metal salts which may be used, sodium and potassium salts are the most important commercially.

In use, improved emulsification or emulsion stability is obtained by providing, in an emulsion of oil and water, at least about 0.001% of a mixture of the taurine and the sulfate or sulfonate detergent based on the weight of the water. For many applications, an amount of emulsifier between about 0.005% and 0.5% is particularly appropriate. However, it will be recognized that higher concentrations of emulsifier may be appropriate for systems which emulsify with greater difficulty.

The invention is further illustrated by the following example.

EXAMPLE Three detergent formulations comprising mixtures of (1)a C C HAMT composition, which is a mixture of hydroxyalkyl-N-methyltaurines having 14 to 16 carbon atoms in the alkyl group, that is R in the general formula is an alkyl having 12 to I14 carbons, and (2) a surface active organic detergent selected from each of the three groups of sulfonate and sulfate detergents disclosed were tested for synergistic effects. The detergents used in these three formulations were:

(1) EMCO, an N-(acyloxyethyl) sulfoacetamide wherein the acyl portion is derived from lauric acid, and the cation is potassium;

(2) Igepon A, an acyl isethionate wherein the acyl portion comprises approximately 45% C 20% C 11% Cg 10, and C16 13 moieties; and

(3) Igepon TC-42, an acylarnidomethanesulfonate wherein the acyl portion is derived from coconut oil having the following approximate fatty acid distribution: 50% c 18% C 15% C 11% saturated c c and 6% olefinically unsaturated C (oleic) moieties.

The N- Z-hydroxyalkyl -N-methyltau rine composition was obtained by reacting a 1,2-epoxyalkane with sodium N-methyltaurine in equimolar proportions. The 1,2- epoxyalkane was in turn obtained by epoxidizing a C C cut from a Ziegler type alpha-olefin.

To evaluate the emulsifying properties conveniently, a special test was devised as follows:

Tap water (480 ml.) was aded to a 600 m1. beaker and heated to approximately F. The particular detergent solution to be studied was added to the Water, followed by the addition of 20 ml. of Wesson Oil. At this point the temperature of the solution was approximately 116 F. The mixture was then stirred for one (1) \minute at 600 r.p.m.s using a C0le-Parmer constant speed motor and control unitModel 4420. Using this equipment, 435 r.p.m.s was found to be too slow for proper agitation. A. metal stirrer with a 5 x 1.6 cm. blade was used, immersed 8 cm. below the surface of the liquid. The emulsion was then allowed to stand at room temperature, and the amount of oil separation was noted as a function of time.

The compositions were all tested in varying proportions of 1:1, 1:3, and 3:1 HAMT to detergent. The results are reported in the following Tables I III:

Ratio, Taurine to Emco Emco detergent system HAMT (0.028%) HAMT (0.021%) Emco (0.007%) TABLE II Ratio, Percent oil separation in time of Taurine to Igepon A detergent system Igepon A hr. 96 hr. )6 hr. 1 hr. 2 hr. 3 hr.

HAMT (0.028%) 0 30 60 70 ?fi i;% (g g%7 0 95 95 95 98 98 ffi%% 8i i /f@: 1:3 0 Tr. Tr.-1 1 gfs i w figg 1:1 0 o 0 o o o Igepon A mooaygiflu 3:1 so so No'rE.-Tr.=trace.

TABLE I11 Ratio, 7 7 V Taurine Percent oil separatino in time of Igepon TC42 to Igepon detergent system CFC-42 hr. it: hr. hr. 1 hr. 2 hr. 4 hr. 5 hr. 6 hr. 7 hr.

HAMT (0.028%) 0 0 0 'lr. 40 50 60 60 65 igepholn '1(C-42 7()).028%) 0 0 0 'Ir.-1 5 8 10 10 10 A T 0.007 %g fi% ;g 1.3 0 0 0 Tr. 1 2 2 2 2 .014 3 2 ;9 014%) 1.1 0 0 0 Ti. Tr. 1 2 2 3 3 l .0 1 lgepon T042 007%) 3.1 Tr. 'Ir. Tr. TL 5 55 60 60 Norm-Tr. =trace.

The results reported in Tables I-III show that marked synergism in oil emulsification is obtained when EMCO, the N-(acyloxyethyl) sulfoacetamide, is employed in a 1:3 ratio, and when Igepon A, the acyl isethionate and Igepon TC-42, the amidomethanesulfonate, are used in a 1:1 and 1:3 ratio with a (I -C HAMT hydroxyalkyl-N-methyltaurine according to the invention. Where either the sulfate detergent or the taurine compound was used separately, far less effective emulsification of the oil was obtained.

Because of its superior ability as an emulsifier the combination of an N-(2-hydroxyalkyl)-N-methyltaurine and a second detergent is of particular value in dishwashing formulations. The dishwashing detergent may be in either liquid or powder form; however, as is well known, the liquid form of detergent is by far the preferred form for consumer acceptance. As a liquid, :1 essentially of (A) from 5% to 21% of one or more surface active organic sulfate and sulfonate detergents as described above, (B) from 9% to 13% of one or more taurine salts, as described above, the ratio of (A) to (B) being between 3:1 and 1:3, depending upon the nature of the sulfate or sulfonate detergent ingredient, and (C) sufficient water to yield a liquid.

A typical formulation embodying the present invention adapted to be used as a liquid dishwashing detergent may have the following composition:

Percent Cm-Cm acyl isethionate 9-13 C C HAMT 9-13 Solubilizers 2-15 Salts 0-4 Opacifier 0-1 Perfume, colorant, etc 00.2

Water, balance to make 100%.

The N-(Z-hydroxyalkyl)-N-methyltaurine used in the liquid embodiment set forth above may be a pure component; however, mixtures in the range of C and C alkyl groups will be of greater practical availability. The cation may be an alkali metal or ammonium ion. Oxa- HAMT may be substituted for HAMT in the same amount. Salts are frequently desired to increase the viscosity of the liquid for purposes of consumer acceptance. Sodium and potassium chlorides, sulfates, monoethanol ammonium sulfates, and bicarbonates are particularly useful in this respect.

With respect to the solubilizers mentioned in the foregoing liquid formulation, all materials commonly classified as solubilizers would be suitable. Included are the various alcohols, preferably the saturated, aliphatic type, which also provide freeze-thaw stability to the detergent. These alcohols may be monoor polyhydric and may contain inert solubilizing groups such as ether linkages. Examples of monohydric alcohols are methyl, ethyl, n-propyl, isopropyl and n-butyl alcohol or mixtures thereof. Higher monohydric alcohols are not preferred since they have a comparatively undesirable odor and generally exhibit less solubility in water. Among the many suitable polyhydric alcohols are ethylene, propylene, and hexylene glycol, glycerol or mixtures thereof. Suitable alcohols possessing ether linkages are the monethyl ethers of ethylene and diethylene glycol, the monobutyl and monomethyl ethers of diethylene glycol, dioxan and the like.

In lieu of the foregoing alcohols, the low molecular weight aryl and alkylaryl sulfonates may also be used as solubilizers, such as the alkali metal alkylarenesulfonates derived from benzene, naphthalene, diphenyl and diphenylmethane. In addition, the soluble alkali metal and ammonium sulfonates of benzene, toluene, cumene and xylene may also be used. Examples are the ethanol, diethanol and triethanol ammonium benzene sulfonates and potassium and sodium toluene sulfonate.

In the present invention, it has been found that detergency is not significantly influenced by pH. However, Where a liquid detergent formulation is desired, the pH level should be above 8 in the detergent concentrate. Below a pH of about 8, the HAMT compounds have limited solubility.

It will be understood that the foregoing disclosure and example are provided to define the invention to meet the requirements of the patent statute and that it is not limited thereto. Many modifications of the invention as defined by the following claims will be apparent to those skilled in the art.

We claim:

1. A composition having improved properties for promoting stabilization of oil and water emulsions consisting essentially of (a) a taurine selected from the group consisting of compounds having the formula wherein R is an alkyl radical having 12 to 18 carbon atoms or an oxaalkyl radical having the formula C H -OCH n being 11 to 17, and M is a water-solubilizing cation; and

(b) a salt of a water-solubiilzing cation with a surface active organic detergent selected from the group consisting of amidomethanesulfonates of the formula 1? R--NH-oH -sonvi in a weight ration of 1:1 to 1:3, taurine to detergent, acyl isethionates of the formula in a weight ratio of 1:1 to 1:3, taurine to detergent, and N-(acyloxyethyl) sulfoacetamides of the formula in a weight ratio of 1:3, taurine to detergent, wherein, in the foregoing formulas, R is an aliphatic hydrocarbon radical having from about 8 to about 20 carbon atoms and M is a water-solubilizing cation. 2. A composition according to claim 1 consisting essentially of:

(a) from about 2% to about 35% of said surface active organic detergent; (b) from about 2% to about 35% of said taurine;

and (0) up to about 55% of a detergent builder. 3. A composition according to claim 1 consisting essentially of:

(a) from about 2% to about 35% of said surface active organic detergent; (b) from about 2% to about 35% of said taurine; (c) from about 0% to about 55% of an alkaline phosphate builder; and (d) from about 0% to about 15% of an organic amide of a fatty acid having from 12 to 22 carbon atoms in which at least one of the hydrogens of the amide nitrogen is replaced by a member selected fro-m the group of lower alkyl and lower alkanol groups. 4. A liquid detergent concentrate consisting essentially of (a) 9% to about 13% of a taurine selected from the group of compounds having the formula wherein R is an alkyl group having from 12 to 18 carbon atoms or an oxaalkyl radical having the formula C H -OCH n being 11 to 17, and M is a water-solubilizing cation;

(b) from about to about 21% of a salt of a watersolubilizing cation with an organic surface active organic detergent selected from the group consisting of amidomethanesulfonates of the formula in a weight ratio of 1:1 to 1:3, taurine to detergent, acyl isethionates of the formula in a weight ratio of 1:1, to 1:3, taurine to detergent, N-acyloxyethyl sulfoacetamides of the formula in a 1:3 weight ratio, wherein, in the foregoing formulas, R is an aliphatic hydrocarbon radical having about 8 to about 20 carbon atoms and M is watersolubilizing cation; and

(c) sufficient water to yield a liquid concentrate having a pH of at least about 8.

5. A liquid detergent concentrate according to claim 4 consisting essentially of:

(a) from 9% to 13% of said isethionate wherein said isethionate has about 12 to about 18 carbon atoms in the acyl portion, and M is a water-solubilizing cation selected from the group consisting of the alkali metals and ammonium;

(b) from 9% to 13% of said taurine, wherein said taurine has from 12 to 14 carbon atoms in R and M is a water-solubilizing cation selected from the group consisting of the alkali metals and ammonium;

(c) from 2% to 15 of a solubilizing agent selected fro-m the group consisting of lower monohydric alkanols, lower alkylene and polyalkylene glycols, lower alkyl ethers of lower alkylene glycols, glycerol and dioXane and lower molecular weight alkali metal and ammonium aryl and lower alkylaryl sulfonates; and

(d) sufficient water to yield a liquid concentrate having a pH of at least about 8.

FOREIGN PATENTS 1/1965 Canada 252153 LEON D. ROSDOL, Primary Examiner D. L. ALBRECHT, Assistant Examiner U.S. Cl. X.R.

252153, 171, 353, 355, 357, 538, 545, 557 DIG. 14; 

